Method for setting subbands in multicarrier communication, and radio communication mobile station apparatus

ABSTRACT

A wireless communication base station apparatus wherein when a frequency scheduling transmission and a frequency diversity transmission are performed in a multicarrier communication at the same time, the adaptive control of a channel for performing the frequency scheduling transmission can be prevented from being complicated. In this apparatus, a modulating part ( 12 ) modulates an encoded Dch data to generate Dch data symbols. A modulating part ( 22 ) modulates an encoded Lch data to generate Lch data symbols. An assigning part ( 103 ) assigns the Dch and Lch data symbols to subcarriers constituting OFDM symbols and outputs them to a multiplexing part ( 104 ). At this moment, the assigning part ( 103 ) assigns a set of Dch and Lch data symbols to each subcarrier for a respective subband.

BACKGROUND

1. Technical Field

The present invention relates to a subband setting method and a radiocommunication mobile station apparatus in multicarrier communication.

2. Description of the Related Art

In recent years, in radio communication, particularly in mobilecommunication, various kinds of information such as images and dataother than speech have become targets of transmission. Demand forhigher-speed transmission is likely to increase in the future, and, torealize high-speed transmission, a radio transmission technique isdesired that realizes high transmission efficiency by utilizing limitedfrequency resources efficiently.

Radio transmission techniques that respond to this demand include OFDM(Orthogonal Frequency Division Multiplexing). OFDM refers to amulticarrier transmission technique for transmitting data in parallelusing a large number of subcarriers, and is known as a technique thathas high frequency efficiency and characteristics of reducinginter-symbol interference under a multipath environment and that iseffective in improving transmission efficiency.

Performing frequency scheduling transmission and frequency diversitytransmission when this OFDM is used in downlink and data for a pluralityof radio communication mobile station apparatuses (hereinafter simply“mobile stations”) is frequency-domain-multiplexed on a plurality ofsubcarriers, is studied (for example, see Non-Patent Document 1).

With frequency scheduling transmission, a radio communication basestation apparatus (hereinafter simply “base station”) allocatessubcarriers to mobile stations adaptively based on received quality ofeach frequency band at the mobile stations, so that it is possible toobtain a maximal multi-user diversity effect and perform communicationvery efficiently. Such frequency scheduling transmission is a schemesuitable for data transmission mainly when the mobile station moves atlow speed. On the other hand, frequency scheduling transmission requiresfeedback of received quality information from the mobile stations and sois not suitable for data transmission when the mobile station moves athigh speed. Further, frequency scheduling is generally performed persubband which is obtained by dividing adjacent subcarriers into blocks,and so cannot provide a very high frequency diversity effect.

In Non-Patent Document 1, a channel for performing this frequencyscheduling transmission is referred to as a localized channel(hereinafter “Lch”). Conventionally, Lchs are allocated in subband unitsor in units of a plurality of consecutive subcarriers. Further,generally, adaptive control such as adaptive modulation is performed onLchs per subband (in the frequency domain) and per subframe (in the timedomain). For example, to achieve a required error rate, the base stationperforms adaptive control on an MCS (Modulation and Coding Scheme) ofLch data symbols based on received quality information fed back from themobile station.

In addition, Non-Patent Document 1 discloses an example where one frame(10 ms) is divided into 20 subframes (one subframe=0.5 ms) and onesubframe includes six or seven OFDM symbols.

By contrast with this, frequency diversity transmission allocates datafor the mobile stations to subcarriers in the full band in a distributedmanner, and so can provide a high frequency diversity effect. Further,frequency diversity transmission does not require received qualityinformation from the mobile stations, and so is an effective scheme in astate to which frequency scheduling transmission is difficult to applyas described above. On the other hand, frequency diversity transmissionis performed regardless of the received quality at the mobile stations,and so cannot provide a multi-user diversity effect as in frequencyscheduling transmission. In Non-Patent Document 1, a channel forperforming such frequency diversity transmission is referred to as adistributed channel (hereinafter “Dch”). Conventionally, Dchs are setaccording to FH (Frequency Hopping) patterns which cover the whole bandof OFDM symbols.

Non-Patent Document 1: R1-050604 “Downlink Channelization andMultiplexing for EUTRA” 3GPP TSG RAN WG1 Ad Hoc on LTE, SophiaAntipolis, France, 20-21 Jun. 2005

BRIEF SUMMARY Problems to be Solved by the Invention

Here, Non-Patent Document 1 sets Dchs according to FH patterns whichcover the whole band of OFDM symbols to perform frequency schedulingtransmission and frequency diversity transmission at the same time, andso Dch data symbols are allocated to subbands to which Lchs areallocated. As a result, when the number of mobile stations communicatingwith the base station changes and the number of settings of Dch changes,the resource size of one Lch, that is, the number of bits transmitted inone subband and one subframe using one Lch changes. That is, the codingblock size of an Lch varies per subframe.

In this way, if the coding block size of an Lch varies per subframe, thecoding gain varies per subframe and the error rate that can be achievedin certain received quality varies per subframe. That is, when Dchs areset according to FH patterns which cover the whole band of OFDM symbolsas disclosed in Non-Patent Document 1, the number of settings of Dchchanges and, consequently, BER (Bit Error Rate) performances of Lchschange. As described above, adaptive control is generally performed persubframe on Lchs, and so, when the number of settings of Dch changes andthe BER performances of Lchs change, the base station needs to changethe correspondence relationship between the received quality and the MCSin adaptive modulation per subframe in accordance with the change of theBER performances, which makes adaptive control for Lchs complicated.

Further, when the number of settings of Dch changes and the coding blocksize of an Lch changes per subframe, the base station needs to reportthe coding block size every time the coding block size changes, to themobile station that receives and decodes data symbols of Lchs, whichmakes design of a communication system complicated.

It is therefore an object of the present invention to provide a subbandsetting method and a base station that, when frequency schedulingtransmission and frequency diversity transmission are performed at thesame time in multicarrier communication, prevent adaptive control for achannel for performing frequency scheduling transmission from becomingcomplicated.

Means for Solving the Problem

The subband setting method of the present invention includes: dividing aplurality of subcarriers forming a multicarrier signal into a pluralityof subbands; and setting in the plurality of subbands both firstsubbands including data for a plurality of radio communication mobilestation apparatuses and second subbands including data for only oneradio communication mobile station apparatus.

Advantageous Effect of the Invention

According to the present invention, when frequency schedulingtransmission and frequency diversity transmission are performed at thesame time in multicarrier communication, it is possible to preventadaptive control for a channel for performing frequency schedulingtransmission from becoming complicated.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a base stationaccording to Embodiment 1 of the present invention;

FIG. 2 shows an example of subband division according to Embodiment 1 ofthe present invention;

FIG. 3 shows a subband setting example according to Embodiment 1 of thepresent invention (setting example 1);

FIG. 4 shows a subband setting example according to Embodiment 1 of thepresent invention (setting example 2);

FIG. 5 shows a subband setting example according to Embodiment 1 of thepresent invention (setting example 3);

FIG. 6 shows a subband setting example according to Embodiment 1 of thepresent invention (setting example 3);

FIG. 7 shows a subband setting example according to Embodiment 1 of thepresent invention (setting example 4);

FIG. 8 shows a subband setting example according to Embodiment 1 of thepresent invention (setting example 5);

FIG. 9 shows a subband setting example according to Embodiment 1 of thepresent invention (setting example 6);

FIG. 10 shows a subband setting example according to Embodiment 1 of thepresent invention (setting example 7);

FIG. 11 is a block diagram showing a configuration of a base stationaccording to Embodiment 2 of the present invention;

FIG. 12 shows a subband setting example according to Embodiment 2 of thepresent invention;

FIG. 13 shows a control information format according to Embodiment 2 ofthe present invention;

FIG. 14 is a block diagram showing a configuration of a base stationaccording to Embodiment 3 of the present invention; and

FIG. 15 shows an example of transmission power control according toEmbodiment 3 of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will be described in detail belowwith reference to the accompanying drawings.

(Embodiment 1)

FIG. 1 shows a configuration of base station 100 according to thisembodiment. Base station 100 divides a plurality of subcarriers thatform an OFDM symbol, which is a multicarrier signal, into a plurality ofsubbands, and sets a Dch or an Lch per subband in these plurality ofsubbands.

Base station 100 includes the same number of encoding and modulatingsections 101-1 to 101-n which are configured with encoding sections 11and modulating sections 12 for Dch data, encoding and modulatingsections 102-1 to 102-n which are configured with encoding sections 21and modulating sections 22 for Lch data, and demodulating and decodingsections 115-1 to 115-n which are configured with demodulating sections31 and decoding sections 32, as mobile stations (MSs) n that basestation 100 can communicate with.

In encoding and modulating sections 101-1 to 101-n, encoding sections 11perform encoding processing such as turbo encoding on Dch data #1 to #nfor each of mobile stations #1 to #n, and modulating sections 12 performmodulating processing on the encoded Dch data to generate Dch datasymbols.

In encoding and modulating sections 102-1 to 102-n, encoding sections 21perform encoding processing such as turbo encoding on Lch data #1 to #nfor each of mobile stations #1 to #n, and modulating sections 22 performmodulating processing on the encoded Lch data to generate Lch datasymbols. In this case, the coding rate and the modulation scheme followMCS information inputted from adaptive controlling section 116.

Allocating section 103 allocates Dch data symbols and Lch data symbolsto subcarriers that form OFDM symbols according to control from adaptivecontrolling section 116, and outputs the results to multiplexing section104. At this time, allocating section 103 allocates Dch data symbols andLch data symbols to subcarriers, respectively, per subband. That is,allocating section 103 allocates the Dch data symbols to Dch subbandsand allocates the Lch data symbols to Lch subbands. Further, allocatingsection 103 outputs Dch data symbol allocating information (i.e.,information showing the Dch data symbol for which mobile station isallocated to which subcarrier) and Lch data symbol allocatinginformation (i.e., information showing the Lch data symbol for whichmobile station is allocated to which subcarrier), to control informationgenerating section 105.

Control information generating section 105 generates control informationcomprised of Dch data symbol allocating information, Lch data symbolallocating information, and MCS information inputted from adaptivecontrolling section 116, and outputs the control information to encodingsection 106.

Encoding section 106 performs encoding processing on the controlinformation, and modulating section 107 performs modulating processingon the encoded control information and outputs the result tomultiplexing section 104.

Multiplexing section 104 multiplexes the control information on the datasymbols inputted from allocating section 103 and outputs the results toIFFT (Inverse Fast Fourier Transform) section 108. The controlinformation is multiplexed, for example, per subframe. Further, in thisembodiment, the control information may be eithertime-domain-multiplexed or frequency-domain-multiplexed.

IFFT section 108 performs an IFFT on a plurality of subcarriers to whichcontrol information and data symbols are allocated, and generates OFDMsymbols, which are multicarrier signals.

CP (Cyclic Prefix) adding section 109 adds the same signal as the tailof each OFDM symbol, to the head of that OFDM symbol as a CP.

Radio transmitting section 110 performs transmitting processing such asD/A conversion, amplification and up-conversion on the OFDM symbols towhich CPs are added, and transmits the results to the mobile stationsfrom antenna 111.

On the other hand, radio receiving section 112 receives n OFDM symbolstransmitted at the same time from a maximum of n mobile stations,through antenna 111, and performs receiving processing such asdown-conversion and D/A conversion on these OFDM symbols.

CP removing section 113 removes the CPs from the OFDM symbols subjectedto the receiving processing.

FFT (Fast Fourier Transform) section 114 performs an FFT on the OFDMsymbols from which the CPs are removed, and obtains signals of eachmobile station, which are multiplexed in the frequency domain. Themobile stations transmit signals using subcarriers or subbands which aredifferent between the mobile stations, and the signals of the mobilestations include received quality information of each subband reportedfrom the mobile stations. The mobile stations can measure receivedquality of each subband using the received SNR, received SIR, receivedCINR, received power, interference power, bit error rate, throughput,MCS that achieves a predetermined error rate, and so on. Further, thereceived quality information may be referred to as “CQI (Channel QualityIndicator),” “CSI (Channel State Information),” and so on.

In demodulating and decoding sections 115-1 to 115-n, demodulatingsections 31 perform demodulating processing on the signals subjected tothe FFT, and decoding sections 32 perform decoding processing on thedemodulated signals. By this means, the received data is obtained. Outof the received data, received quality information of each subband isinputted to adaptive controlling section 116.

Adaptive controlling section 116 performs adaptive control on the Lchdata based on the received quality information of each subband reportedfrom the mobile stations. That is, adaptive controlling section 116selects an MCS that achieves a required error rate per subband andoutputs MCS information based on the received quality information ofeach subband, for encoding and modulating sections 102-1 to 102-n, andperforms frequency scheduling of determining to which subcarriers Lchdata #1 to #n are allocated, in subband units using a schedulingalgorithm such as the Max SIR method and the proportional fairnessmethod, for allocating section 103. Further, adaptive controllingsection 116 outputs the MCS information of each subband to controlinformation generating section 105.

Next, the subband setting example according to this embodiment will bedescribed. As shown in FIG. 2, a case will he described below as anexample where one OFDM symbol is formed with subcarriers f₁ to f₇₂, andthese subcarriers are equally divided into subbands (SB) 1 to 12.Therefore, one subband includes six subcarriers. Further, one subframeincludes six OFDM symbols. Furthermore, although a case will bedescribed where setting of subbands as described below is made inallocating section 103 in advance, the present invention is not limitedto this and setting of subbands may change per sub frame.

<Subband Setting Example 1 (FIG. 3)>

In this setting example, as shown in FIG. 3, subbands 1, 4, 7 and 10 areset as Dch subbands, and subbands 2, 3, 5, 6, 8, 9, 11 and 12 are set asLch subbands. That is, in subbands 1 to 12, Dch subbands (subbands thataccommodate only Dch) are set at fixed intervals and arrangedperiodically.

Here, frequency scheduling is performed in subband units for an Lch, andso each Lch subband includes an Lch data symbol for only one mobilestation. That is, one subband forms one Lch for one mobile station. Inthe example shown in FIG. 3, eight Lchs of Lchs 1 to 8 are set.

On the other hand, frequency diversity transmission needs to beperformed on the Dchs, and so Dch subbands 1, 4, 7 and 10 include Dchdata symbols for a plurality of mobile stations. In the example shown inFIG. 3, each Dch subband includes Dch data symbols for six mobilestations. That is, in each Dch subband, a plurality of Dchs for aplurality of mobile stations are frequency-domain-multiplexed.Therefore, in the example shown in FIG. 3, four Dch subbands each formDchs 1 to 6 for six mobile stations.

In this setting example, eight Lchs and six Dchs arefrequency-domain-multiplexed in this way.

In this way, in this embodiment, Dchs are not set according to FHpatterns that cover the whole band f₁ to f₇₂ of the OFDM symbols, butare set in subband units instead, and so Dch data symbols are notallocated to the Lch subbands. Therefore, even if the number of mobilestations that communicate with base station 100 changes and the numberof settings of Dch changes, the coding block size of each Lch ismaintained fixed at “one subband×one subframe.” Consequently, accordingto this embodiment, when frequency scheduling transmission in Lchs andfrequency diversity transmission in Dchs are performed at the same time,it is possible to prevent adaptive control for Lchs from becomingcomplicated. Further, even if the number of settings of Dch changes, thecoding block size of each Lch is maintained fixed at “one subband×onesubframe,” and so it is not necessary to report the coding block size tothe mobile stations and facilitate design of a communication system.

<Subband Setting Example 2 (FIG. 4)>

Frequency scheduling transmission is not suitable for a mobile stationthat moves at high speed as described above, and so base station 100transmits data to the mobile station that moves at high speed using Dchsout of Lchs and Dchs. In this setting example, the number of settings ofDch is changed per cell according to the number of mobile stations thatmove at high speed (mobile stations whose moving speed exceeds athreshold). That is, as shown in FIG. 4, when the number of mobilestations that move at high speed increases, the number of settings ofDch is increased. In FIG. 3, eight Lchs and six Dchs arefrequency-domain-multiplexed, while, in FIG. 4, by setting subbands 1,2, 4, 5, 7, 8, 10 and 11 as Dch subbands, and setting subbands 3, 6, 9and 12 as Lch subbands, four Lchs and twelve Dchs arefrequency-domain-multiplexed. By this means, when the number of mobilestations that move at high speed increases, the number of mobilestations to which base station 100 can transmit data using Dchs, can beincreased.

<Subband Setting Example 3 (FIGS. 5 and 6)>

In a plurality of subbands 1 to 12 in one OFDM symbol, when interval 41between a plurality of Dch subbands that include Dch data symbols to thesame mobile station, becomes smaller, the number of Dch subbands formingone Dch increases, and so a frequency diversity effect becomes high.Therefore, in this setting example, in a channel environment where delaydispersion in a channel is large, as in a macro cell (that is, fadingfluctuation in the frequency domain in the channel is fast and thecoherent bandwidth of the channel is narrow), to obtain a high frequencydiversity effect, interval 41 is set small as shown in FIG. 5. In achannel environment where delay dispersion in a channel is small, as ina micro cell, (that is, fading fluctuation in the frequency domain inthe channel is slow and the coherent bandwidth of the channel is wide),the frequency diversity effect is less likely to be obtained, and sointerval 41 is set large as shown in FIG. 6. That is, in this settingexample, when delay dispersion in the channel becomes larger, theinterval of setting a plurality of Dch subbands that include Dch datasymbols for the same mobile station, is made smaller.

Further, the data amount of Dch data transmitted to the mobile stationsusing one OFDM symbol is made fixed regardless of the size of setinterval 41. Therefore, when interval 41 is set small as shown in FIG.5, the number of subcarriers allocated to one mobile station in each Dchsubband is reduced and the number of mobile stations for which frequencymultiplexing is performed is increased. When interval 41 is set large asshown in FIG. 6, the number of subcarriers allocated to one mobilestation in each Dch subband is increased and the number of mobilestations for which frequency multiplexing is performed is reduced. To bemore specific, the number of mobile stations for which frequencymultiplexing is performed in each Dch subband is six in the case of FIG.5, while three in the case of FIG. 6. That is, in this setting example,when delay dispersion in the channel becomes larger, interval 41 is madesmaller and the number of mobile stations for which frequencymultiplexing is performed in each Dch subband is increased.

In this way, in this setting example, when delay dispersion in thechannel is small, as shown in FIG. 6, interval 41 is made large, and thenumber of mobile stations for which frequency multiplexing is performedin each Dch subband is reduced. Therefore, according to this settingexample, when delay dispersion in the channel is small (in the case ofFIG. 6), the number of Dchs can be increased or decreased in smallerunits than the case where delay dispersion in the channel is large (inthe case of FIG. 5). To be more specific, in the case of FIG. 5, Dchsneed to be increased or decreased by six channels, while, in the case ofFIG. 6, Dchs can be increased or decreased by three channels. In thisway, according to this setting example, when delay dispersion in thechannel is small, the ratio between the number of Lchs and the number ofDchs can be set more flexibly than the case where delay dispersion inthe channel is large.

<Subband Setting Example 4 (FIG. 7)>

Although, in setting examples 1 to 3, a plurality of Dchs arefrequency-domain-multiplexed in each Dch subband, in this settingexample, as shown in FIG. 7, a plurality of Dchs aretime-domain-multiplexed in each Dch subband. That is, in this settingexample, time multiplexing is performed for a plurality of mobilestations in Dch subbands. By this means, it is possible to obtain afrequency diversity effect in the Dchs. Further, the mobile stationneeds to perform receiving processing such as an FFT only in periodallocated to the mobile station, so that it is possible to reduce powerconsumption of the mobile station. Furthermore, base station 100transmits Dch data symbol allocating information earlier than othercontrol information such as MCS information or performs simple encodingon Dch data symbol allocating information to allow the mobile station toknow earlier the period for which Dchs for the mobile station areallocated, and stop receiving processing earlier, so that it is possibleto further reduce power consumption of the mobile station.

<Subband Setting Example 5 (FIG. 8)>

In this setting example, in addition to setting example 4 (FIG. 7), asfurther shown in FIG. 8, positions where Dchs aretime-domain-multiplexed are made different in a plurality of Dchsubbands. That is, in this setting example, in the plurality of Dchsubbands, positions where the plurality of mobile stations for whichtime multiplexing is performed, are made different. By this means, forthe Dchs, it is possible to obtain a diversity effect not only in thefrequency domain but also in the time domain. Furthermore, when pilotsignals are arranged before and after each subframe, there are partsthat are close to the pilot signals and have good channel estimationaccuracy and parts that are far from the pilot signals and have poorchannel estimation accuracy in each subband, and so, by making positionswhere Dchs are time-domain-multiplexed different in the plurality of Dchsubbands as in this setting example, it is possible to equalize channelestimation accuracy of Dchs.

<Subband Setting Example 6 (FIG. 9)>

In this setting example, as shown in FIG. 9, Dch data symbols for themobile stations are frequency-hopped in each Dch subband. By this means,it is possible to obtain a diversity effect against fluctuation in thetime domain and the frequency domain in the Dch subbands.

<Subband Setting Example 7 (FIG. 10)>

In this setting example, as shown in FIG. 10, positions where Dchsubbands are set in subbands 1 to 12 are changed per subframe. By thismeans, it is possible to further improve a frequency diversity effectfor Dchs. Further, according to this setting example, subbands havinghigh received quality at the mobile station are not used continuously asDchs. That is, subbands having low received quality at the mobilestation are not used continuously as Lchs, so that it is possible toimprove throughput of Lchs.

Subband setting examples 1 to 7 according to this embodiment have beendescribed.

In this way, according to this embodiment, when frequency schedulingtransmission for Lchs and frequency diversity transmission for Dchs areperformed at the same time, the Dchs and Lchs are set per subband, sothat it is possible to prevent adaptive control for the Lchs frombecoming complicated. Further, if the number of settings of Dch changes,the coding block size of each Lch is maintained fixed at “onesubband×one subframe,” and so it is not necessary to report the codingblock size to the mobile stations. Further, Dch subbands are set atfixed intervals and arranged periodically, and so it is not necessary toreport position information of the Dch subbands to the mobile stations.Therefore, according to this embodiment, design of a communicationsystem becomes simple.

In addition, intervals between Dch subbands do not necessarily have tobe fixed, and if the intervals are set in advance, the above-describedeffects can be obtained.

Further, in the above description, although allocation information forDch data symbols and allocation information for Lch data symbols areinputted from allocating section 103 to control information generatingsection 105, these allocation information may be directly inputted fromadaptive controlling section 116 to control information generatingsection 105. In this case, MCS information, allocation information forDch data symbols and allocation information for Lch data symbols areinputted from allocating section 103 to control information generatingsection 105.

(Embodiment 2)

The base station according to this embodiment differs from Embodiment 1in that Dch subbands are made different per mobile station according tothe level of delay dispersion in a channel of each mobile station.

The configuration of base station 200 according to this embodiment isshown in FIG. 11. In FIG. 11, components that are the same as those inEmbodiment 1 (FIG. 1) will be assigned the same reference numeralswithout further explanations.

In base station 200, channel fluctuation measuring section 201 receivesthe signal of each mobile station, obtained by FFT section 114. Channelfluctuation measuring section 201 measures the level of channelfluctuation in the frequency domain per mobile station, that is,measures the level of delay dispersion in the channel of each mobilestation, using the pilot signal included in the signal of each mobilestation, and outputs the result to allocating section 103.

Allocating section 103 allocates Dch data symbols for the mobilestations, to Dch subbands according to the level of delay dispersion inthe channel of each mobile station as described below.

That is, in this embodiment, as shown in FIG. 12, Dch subbands areclassified into subbands having large setting interval 41 and subbandshaving small setting interval 41. That is, in one OFDM symbol, both Dchsubbands having large setting interval 41 and Dch subbands having smallsetting interval 41 are set.

In addition, this setting interval 41 is the same as setting interval 41in subband setting example 3 of Embodiment 1. Further, as in subbandsetting example 3, in this embodiment, the data amount of Dch datatransmitted to the mobile stations using one OFDM symbol is made fixedregardless of the size of setting interval 41. Therefore, as shown inFIG. 12, in Dch subbands having small setting interval 41, the number ofDch subbands is large, and so the number of subcarriers allocated forone mobile station is reduced and the number of mobile stations forwhich frequency multiplexing is performed is increased, and, in Dchsubbands having large setting interval 41, the number of Dch subbands issmall, and so the number of subcarriers allocated for one mobile stationis increased and the number of mobile stations for which frequencymultiplexing is performed is reduced.

In subbands 1 to 12, allocating section 103 allocates Dch data symbolsfor the mobile station having small delay dispersion in a channel, toDch subbands (subbands 1 and 7) which have large setting interval 41,and allocates Dch data symbols for the mobile station having large delaydispersion in a channel, to Dch subbands (subbands 2, 5, 8 and 11) whichhave small setting interval 41. In addition, allocating section 103judges whether delay dispersion in the channel is small or large permobile station by comparing the value of delay dispersion in the channelfor each mobile station with a threshold.

In this way, this embodiment sets a plurality of Dch subbands, which aresuitable for channel environments of the mobile stations, respectively,in one OFDM symbol, so that it is possible to obtain a required andsufficient frequency diversity effect per mobile station.

Next, the format of control information according to this embodimentwill be described. Control information generating section 105 in basestation 200 generates control information according to the format shownin FIG. 13. In the format shown in FIG. 13, ID of the mobile station,which is a transmission destination of data symbols, is set in “MS-ID,”classification information showing either Dch or Lch is set in “channelclassification,” the Dch subband number or the Lch subband number is setin “subband number,” and MCS information for each subband is set in “MCSinformation.” In addition, in “channel classification,” the intervalsbetween Dch subbands may be set in addition to the above-describedclassification information. For example, control information generatingsection 105 may select and set one of “Lch,” “Dch having intervals oftwo subbands,” “Dch having intervals of three subbands” and “Dch havingintervals of six subbands” in “channel classification.”

The control information generated in this way is time-domain-multiplexedon the head of the subframe by multiplexing section 104 as shown in FIG.12, and transmitted to all mobile stations as SCCH (Shared ControlChannel) control data. That is, in this embodiment, the setting resultsof Dch subbands and Lch subbands in subbands 1 to 12 are reported to themobile stations using one control information that has a format commonto all mobile stations.

In this way, in this embodiment, the setting results of Dch subbands andLch subbands are reported to the mobile stations at the same time usingcontrol information having a format common to all mobile stations, sothat, even if the numbers of Dchs and Lchs change per subframe, controlinformation can be transmitted without wasting resources for data symboltransmission use. Further, one control information format, which iscommon to Dchs and Lchs, is used, so that design of a communicationsystem becomes simple.

In this embodiment, although the level of channel fluctuation of eachmobile station is measured at base station 200, the level of channelfluctuation may be measured at each mobile station and the measuredresult may be reported to base station 200.

Further, it is also possible to use the control information format shownin FIG. 13 in Embodiment 1. In this case, classification informationshowing either a Dch or an Lch, is set in “channel classification.”

(Embodiment 3)

The base station according to this embodiment is different from that inEmbodiment 1 in that the base station performs transmission powercontrol per subband.

Techniques for reducing interference between cells include a techniquecalled “interference coordination.” With interference coordination, thebase station of each cell coordinates in allocating resources andcoordinates in performing transmission power control, and therebyinterference between cells is reduced. This embodiment applies thisinterference coordination to Embodiment 1.

The configuration of base station 300 according to this embodiment isshown in FIG. 14. In FIG. 14, components that are the same as those inEmbodiment 1 (FIG. 1) will be assigned the same reference numeralswithout further explanations.

In base station 300, transmission power controlling section 301 performstransmission power control on Dch data symbols and Lch data symbols persubband. To be more specific, base stations 300 of the cells which areadjacent to each other, perform transmission power control as shown inFIG. 15. That is, base station 300 of cell 1 sets transmission powerhigh, medium, low, high, medium, low, . . . , in that order, fromsubband 1, in subbands 1 to 12. Base station 300 of cell 2 setstransmission power medium, low, high, medium, low, high, . . . , in thatorder, from subband 1, in subbands 1 to 12. Further, base station 300 ofcell 3 sets transmission power as low, high, medium, low, high, medium,. . . , in that order, from subband 1, in subbands 1 to 12. The “high,”“medium,” and “low” transmission power is as follows: for example, whentransmission power “medium” is set as a reference (0 dB), “high”transmission power refers to transmission power 5 dB higher than thereference, and “low” transmission power refers to transmission power 5dB lower than the reference. In this way, by making transmission powerin the same subband different between cells, it is possible to realizeinterference coordination and reduce interference between cells.

Further, conventionally, interference coordination needs to be performedbetween Dchs or Lchs, and so it is necessary to make the number of Dchsand the number of Lchs the same between cells. By contrast with this, asdescribed in Embodiment 1, when Dch subbands and Lch subbands are set,even if the number of Dchs and the number of Lchs are set freely in eachcell, it is possible to realize interference coordination as shown inFIG. 15.

Further, conventionally, interference coordination needs to be performedbetween Dchs, and so the transmission power of Dchs cannot be set “high”in all cells that are adjacent to each other. By contrast with this, ifDch subbands are set as described in Embodiment 1, it is possible to setthe transmission power of Dchs “high” in all adjacent cells as shown inFIG. 15.

Embodiments of the present invention have been described.

Although a case has been described with the above-described embodimentswhere a signal received at the base station (that is, a signaltransmitted by the mobile station in uplink) is transmitted based on theOFDM scheme, this signal may be transmitted based on other transmissionschemes other than the OFDM scheme, such as a single carrier scheme andthe CDMA scheme.

Further, a case has been described with the above-described embodimentswhere adaptive modulation is performed on only Lchs, adaptive modulationmay be also performed on Dchs in the same way.

Still further, an Lch may be referred to as a “frequency schedulingchannel,” and a Dch may be referred to as a “frequency diversitychannel.”

Furthermore, a mobile station, a base station apparatus and a subcarriermay be referred to as “UE,” “Node B” and “tone,” respectively. Further,a subband may be referred to as a “sub-channel,” “subcarrier block,”“resource block” or “chunk.” Still further, a CP may be referred to as a“guard interval (GI).”

Each function block used to explain the above-described embodiments maybe typically implemented as an LSI constituted by an integrated circuit.These may be individual chips or may be partially or totally containedon a single chip. Here, each function block is described as an LSI, butthis may also be referred to as “IC”, “system LSI”, “super LSI”, or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of a programmableFPGA (Field Programmable Gate Array) or a reconfigurable processor inwhich connections and settings of circuit cells within an LSI can bereconfigured is also possible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the development of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

The present application is based on Japanese Patent Application No.2005-321110, filed on Nov. 4, 2005, the entire content of which isexpressly incorporated by reference herein.

Industrial Applicability

The present invention can be applied to a mobile communication systemand the like.

The invention claimed is:
 1. A transmitting apparatus comprising: amapping section which, in operation, maps either a first block, to whichdata indicated by a single resource index are localizedly allocated, oreach of a plurality of second blocks, to which data indicated by thesingle resource index are distributedly allocated, to each of aplurality of blocks, into which a plurality of consecutive subcarriersin a frequency domain and a subframe are divided and each of which iscomprised of the same number of subcarriers; and a transmitter which, inoperation, transmits the data, wherein the plurality of second blocks,to which the data indicated by the single resource index are allocated,are mapped to the plurality of blocks with a predetermined gap such thatthe data indicated by the single resource index are distributed in thefrequency domain, and a resource size for the data indicated by thesingle resource index in the plurality of second blocks is constantregardless of variation of the predetermined gap, and wherein aplurality of data sets indicated by different resource indices aremultiplexed in the plurality of second blocks, and a number of theplurality of second blocks used to transmit one of the data setsindicated by the single resource index in the subframe is the same as anumber of the plurality of data sets multiplexed in one of the pluralityof second blocks.
 2. The transmitting apparatus according to claim 1,wherein the first block or the plurality of second blocks is variablymapped per each of the plurality of blocks.
 3. The transmittingapparatus according to claim 1, wherein the first block or the pluralityof second blocks is variably mapped per each subframe.
 4. Thetransmitting apparatus according to claim 1, wherein a plurality of datasets for a plurality of different receiving apparatuses aretime-multiplexed in the plurality of second blocks.
 5. The transmittingapparatus according to claim 1, wherein in the plurality of secondblocks, the data indicated by the single resource index are allocated indifferent positions in a time domain.
 6. The transmitting apparatusaccording to claim 1, wherein the first block is used in a frequencyscheduling transmission.
 7. The transmitting apparatus according toclaim 1, wherein the plurality of second blocks is used in a frequencydiversity transmission.
 8. The transmitting apparatus according to claim1, wherein the resource size is defined by a number of subcarriers usedto transmit the data indicated by the single resource index in asubframe.
 9. The transmitting apparatus according to claim 1, whereinthe resource size is defined by a number of units used to transmit thedata indicated by the single resource index in a subframe, wherein eachunit is defined as “one subcarrier x one symbol.”
 10. The transmittingapparatus according to claim 1, wherein a resource size for the dataindicated by the single resource index in the first block is the same asa resource size for the data indicated by the single resource index inthe plurality of second blocks in a subframe.
 11. A receiving apparatuscomprising: a receiver which, in operation, receives data in a pluralityof blocks, wherein either a first block, to which data indicated by asingle resource index are localizedly allocated, or each of a pluralityof second blocks, to which data indicated by the single resource indexare distributedly allocated, is mapped to each of the plurality ofblocks, into which a plurality of consecutive subcarriers in a frequencydomain and in a subframe are divided and each of which is comprised of asame number of subcarriers, wherein the plurality of second blocks, towhich the data indicated by the single resource index are allocated, aremapped to the plurality of blocks with a predetermined gap such that thedata indicated by the single resource index are distributed in thefrequency domain, and a resource size for the data indicated by thesingle resource index in the plurality of second blocks is constantregardless of variation of the predetermined gap, and wherein aplurality of data sets indicated by different resource indices aremultiplexed in the plurality of second blocks, and a number of theplurality of second blocks used to transmit one of the data setsindicated by the single resource index in the subframe is the same as anumber of the plurality of data sets multiplexed in one of the pluralityof second blocks.
 12. The receiving apparatus according to claim 11,wherein the first block or the plurality of second blocks is variablymapped per each of the plurality of blocks.
 13. The receiving apparatusaccording to claim 11, wherein the first block or the plurality ofsecond blocks is variably mapped per each subframe.
 14. The receivingapparatus according to claim 11, wherein a plurality of data sets for aplurality of different mobile stations are time-multiplexed in theplurality of second blocks.
 15. The receiving apparatus according toclaim 11, wherein in the plurality of second blocks, the data indicatedby the single resource index are allocated in different positions in atime domain.
 16. The receiving apparatus according to claim 11, whereinthe first block is used in a frequency scheduling transmission.
 17. Thereceiving apparatus according to claim 11, wherein the plurality ofsecond blocks is used in a frequency diversity transmission.
 18. Thereceiving apparatus according to claim 11, wherein the resource size isdefined by a number of subcarriers used to transmit the data indicatedby the single resource index in a subframe.
 19. The receiving apparatusaccording to claim 11, wherein the resource size is defined by a numberof units used to transmit the data indicated by the single resourceindex in a subframe, wherein each unit is defined as “one subcarrier xone symbol.”
 20. The receiving apparatus according to claim 11, whereina resource size for the data indicated by the single resource index inthe first block is the same as a resource size for the data indicated bythe single resource index in the plurality of second blocks in asubframe.
 21. A transmitting method comprising: mapping either a firstblock, to which data indicated by a single resource index arelocalizedly allocated, or each of a plurality of second blocks, to whichdata indicated by the single resource index are distributedly allocated,to each of a plurality of blocks, into which a plurality of consecutivesubcarriers in a frequency domain and a subframe are divided and each ofwhich is comprised of the same number of subcarriers; and transmittingthe data, wherein the plurality of second blocks, to which the dataindicated by the single resource index are allocated, are mapped to theplurality of blocks with a predetermined gap such that the dataindicated by the single resource index are distributed in the frequencydomain, and a resource size for the data indicated by the singleresource index in the plurality of second blocks is constant regardlessof variation of the predetermined gap, and wherein a plurality of datasets indicated by different resource indices are multiplexed in theplurality of second blocks, and a number of the plurality of secondblocks used to transmit one of the data sets indicated by the singleresource index in the subframe is the same as a number of the pluralityof data sets multiplexed in one of the plurality of second blocks.
 22. Areceiving method comprising: receiving data in a plurality of blocks,wherein either a first block, to which data indicated by a singleresource index are localizedly allocated, or each of a plurality ofsecond blocks, to which data indicated by the single resource index aredistributedly allocated, is mapped to each of the plurality of blocks,into which a plurality of consecutive subcarriers in a frequency domainand in a subframe are divided and each of which is comprised of a samenumber of subcarriers, wherein the plurality of second blocks, to whichthe data indicated by the single resource index are allocated, aremapped to the plurality of blocks with a predetermined gap such that thedata indicated by the single resource index are distributed in thefrequency domain, and a resource size for the data indicated by thesingle resource index in the plurality of second blocks is constantregardless of variation of the predetermined gap, and wherein aplurality of data sets indicated by different resource indices aremultiplexed in the plurality of second blocks, and a number of theplurality of second blocks used to transmit one of the data setsindicated by the single resource index in the subframe is the same as anumber of the plurality of data sets multiplexed in one of the pluralityof second blocks.